Bone Interface Research Articles

Effects of immediate loading directionality on the mechanical sensing protein PIEZO1 expression and early-stage healing process of peri-implant bone

BackgroundThe reduced treatment time of dental implants with immediate loading protocol is an appealing solution for dentists and patients. However, there remains a significant risk of early peri-implant bone response following the placement of immediately loaded implants, and limited information is available regarding loading directions and the associated in vivo characteristics of peri-implant bone during the early stages. This study aimed to investigate the effects of immediate loading directionality on the expression of mechanical sensing protein PIEZO1 and the healing process of peri-implant bone in the early stage.MethodsThirty-two implants were inserted into the goat iliac crest models with 10 N static lateral immediate loading applied, followed by histological, histomorphological, immunohistochemical, X-ray microscopy and energy dispersive X-ray spectroscopy evaluations conducted after 10 days.ResultsFrom evaluations at the cellular, tissue, and organ levels, it was observed that the expression of mechanical sensing protein PIEZO1 in peri-implant bone was significantly higher in the compressive side compared to the tensile side. This finding coincided with trends observed in interfacial bone extracellular matrix (ECM) contact percentage, bone mass, and new bone formation.ConclusionsThis study provides a novel insight into the immediate loading directionality as a potential influence factor for dental implant treatments by demonstrating differential effects on the mechanical sensing protein PIEZO1 expression and related early-stage healing processes of peri-implant bone. Immediate loading directions serve as potential therapeutic influence factors for peri-implant bone during its early healing stage.

Exploratory neutron tomography of articular cartilage

To investigate the feasibility of using neutron tomography to gain new knowledge of human articular cartilage degeneration in osteoarthritis (OA). Different sample preparation techniques were evaluated to identify maximum intra-tissue contrast. Human articular cartilage samples from 14 deceased donors (18-75 years, 9 males, 5 females) and 4 patients undergoing total knee replacement due to known OA (all female, 61-75 years) were prepared using different techniques: control in saline, treated with heavy water saline, fixed and treated in heavy water saline, and fixed and dehydrated with ethanol. Neutron tomographic imaging (isotropic voxel sizes from 7.5 to 13.5µm) was performed at two large scale facilities. The 3D images were evaluated for gradients in hydrogen attenuation as well as compared to images from absorption X-ray tomography, magnetic resonance imaging, and histology. Cartilage was distinguishable from background and other tissues in neutron tomographs. Intra-tissue contrast was highest in heavy water-treated samples, which showed a clear gradient from the cartilage surface to the bone interface. Increased neutron flux or exposure time improved image quality but did not affect the ability to detect gradients. Samples from older donors showed high variation in gradient profile, especially from donors with known OA. Neutron tomography is a viable technique for specialized studies of cartilage, particularly for quantifying properties relating to the hydrogen density of the tissue matrix or water movement in the tissue.

Rapamycin facilitates healing of the tendon-bone interface in an aging rat model of chronic rotator cuff injury

BackgroundTendon–bone interface (TBI) healing in chronic rotator cuff injury (CRCI) in older individuals is a common clinical challenge due to cellular senescence, as well as decreased tissue repair and regeneration. Many studies have demonstrated the anti-aging, improved tissue repair, and bone regeneration properties of rapamycin (RPM) in multiple age-related diseases. This study aimed to explore the effects of RPM on TBI healing after CRCI in an aging rat model. MethodsA CRCI model was established in 60 Sprague–Dawley rats (24 months old). Rats were then randomly allocated into the control, 0.1 μg RPM, and 1 μg RPM groups. At 4 and 8 weeks post-reconstructive surgery, the supraspinatus tendon–humerus complexes were harvested for biomechanical, microimaging, histological, and immunohistochemical evaluations. ResultsBiomechanical testing results demonstrated that the failure load, ultimate strength, and stiffness of the two RPM groups were significantly higher than those of the control group at 4 and 8 weeks postoperatively. Microradiographically, both RPM groups had significantly higher values of bone mineral density and the ratio of trabecular bone volume to total volume than controls at each time point. Moreover, the RPM groups had higher histological scores and showed better regenerated TBI, characterized by better organizational tissue, more fibrocartilage cells, and more bone formation. Immunohistochemical evaluations showed that RUNX2-, SOX9-, and SCX-positive cells were significantly more in the two RPM groups than in the controls at each time point. ConclusionsRPM may effectively enhance CRCI healing after reconstruction by facilitating osteogenesis, tenogenesis, and fibrocartilage reformation at the TBI, as well as improving biomechanical properties.

Dual cross-linked COL1/HAp bionic gradient scaffolds containing human amniotic mesenchymal stem cells promote rotator cuff tendon–bone interface healing

The tendon-bone interface heals through scar tissue, while the lack of a natural interface gradient structure and collagen fibre alignment leads to the occurrence of retearing. Therefore, the promotion of tendon healing has become the focus of regenerative medicine. The purpose of this study was to develop a gradient COL1/ hydroxyapatite (HAp) biomaterial loaded with human amniotic mesenchymal stem cells (hAMSCs). The performance of common cross-linking agents, Genipin, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS), and dual cross-linked materials were compared to select the best cross-linking mechanism to optimize the biological and mechanical properties of the scaffold. The optimal COL1/HAp-loaded with hAMSCs were implanted into the tendon-bone rotator cuff interfaces in rats and the effect on the tendon-bone healing was assessed by micro-CT, histological analysis, and biomechanical properties. The results showed that Genipin and EDC/NHS dual cross-linked COL1/HAp had good biological activity and mechanical properties and promoted the proliferation and differentiation of hAMSCs. Animal experiments showed that the group using a scaffold loaded with hAMSCs had excellent continuity and orientation of collagen fibers, increased fibrocartilage and bone formation, and significantly higher biomechanical functions than the control group at the interface at 12 weeks post operation. This study demonstrated that dual cross-linked gradient COL1/HAp-loaded hAMSCs could promote interface healing, thereby providing a feasible strategy for tendon-bone interface regeneration.

0D Amplification Strategies Reshape Bone Interface Niches via Biointernalization Effects

Abstract0D biomaterials (0DBMs) can serve as carriers to enhance and extend the regulatory effects of biological cues they transport on cell fate via bacterial/mammalian cell internalization. However, accurately delivering and amplifying biosignals through 0DBMs remains challenging to cope with ecological niche destabilization induced by factors such as trauma or infection. Herein, the “zero‐dimensional amplification” approach is employed to develop a surface carboxylate carbon dot (CQD‐COOH) conjugated with a neutrophil constitutive peptide (LL‐37), resulting in the formation of a 0D peptide quantum dot (LQD). Hydrogel‐released LQDs, when internalized by bacteria, cause the bacteria to programmatically rupture and die, whereas LQDs internalized by mesenchymal stem cells (MSCs) activate the cellular CXCL12/CXCR4 signaling axis, which directs the stem cells to homing and anchor to the surface of the hydrogel coating. Notably, this strategy of “zero‐dimensional amplification” enables the antimicrobial performance of LL‐37 to be boosted approximately 1.3‐fold, significantly extending the transmission efficiency of biosignals. Meanwhile, 0D lipid nanoparticles (lipo‐NPs) with targeting function incorporated into the hydrogel could deliver the bio‐small molecule MK‐4 to MCSs and induce their endocytosis, further enhancing osseointegration. Thus, the hydrogel coating (HGLL) under this strategy can significantly remodel the ecological niche of the implant–bone interface in infected environment.

Unilateral external fixator and its biomechanical effects in treating different types of femoral fracture: A finite element study with experimental validated model

Previous works had successfully demonstrated the clinical effectiveness of unilateral external fixator in treating various types of fracture, ranging from the simple type, such as oblique and transverse fractures, to complex fractures. However, literature that investigated its biomechanical analyses to further justify its efficacy is limited. Therefore, this paper aimed to analyse the stability of unilateral external fixator for treating different types of fracture, including the simple oblique, AO32C3 comminuted, and 20 mm gap transverse fracture. These fractures were reconstructed at the distal diaphysis of the femoral bone and computationally analysed through the finite element method under the stance phase condition. Findings showed a decrease in the fixation stiffness in large gap fracture (645.2 Nmm-1 for oblique and comminuted, while 23.4 Nmm-1 for the gap fracture), which resulted in higher displacement, IFM and stress distribution at the pin bone interface. These unfavourable conditions could consequently increase the risk of delayed union, pin loosening and infection, as well as implant failure. Nevertheless, the stress observed on the fracture surfaces was relatively low and in controlled amount, indicating that bone unity is still allowable in all models. Briefly, the unilateral fixation may provide desirable results in smaller fracture gap, but its usage in larger gap fracture might be alarming. These findings could serve as a guide and insight for surgeons and researchers, especially on the biomechanical stability of fixation in different fracture types and how will it affect bone unity.

[Artículo traducido] Aparición temprana de líneas radiolúcidas alrededor de la artroplastia total de rodilla en pacientes con artritis reumatoide. ¿Cuál es su impacto en la tasa de fracaso aséptico y los resultados funcionales a los 13 años de seguimiento?

IntroductionAseptic total knee arthroplasty (TKA) failure has been associated with radiolucent lines. This study aimed to determine the impact of the early appearance of radiolucent lines (linear images of 1, 2, or > 2mm at the cement–bone interface) around the TKA on prosthetic survival and functional outcomes in rheumatoid arthritis (RA) patients during a 2–20 years follow-up. MethodsWe retrospectively analyzed a consecutive series of RA patients treated with TKA between 2000 and 2011. We comparatively analyzed patients with and without radiolucent lines around implants. Clinical outcomes were assessed with the knee society score (KSS) collected before surgery, at years 2, 5, and 10, and at the last postoperative follow-up. The knee society roentgenographic evaluation system was used to analyze the impact of radiolucent lines around the implants at 1, 2, 5, and more than ten years of follow-up. The reoperation and prosthetic survival rates were calculated at the end of the follow-up. ResultsThe study series included 72 TKAs with a median follow-up of 13.2 years (range: 4.0–21.0), of which 16 (22.2%) had radiolucent lines. We did not observe aseptic failure, and prosthetic survival at the end of the study was 94.4% (n=68). The KSS improved significantly (p<0.001) between preoperative values at 2, 5, and 10 years and the end of follow-up, with no differences between patients with and without radiolucent lines. ConclusionsOur study demonstrates that the early appearance of radiolucent lines around a TKA in RA patients does not significantly impact prosthetic survival or long-term functional outcomes at 13 years of follow-up.

Effect of bone marrow aspiration concentrate and platelet-rich plasma combination in anterior cruciate ligament reconstruction: a randomized, prospective, double-blinded study

BackgroundThe effect of bone marrow aspirate concentrate (BMAC) and platelet-rich plasma (PRP) combination in enhancing graft maturation and tendon–bone tunnel interfacial healing after anterior cruciate ligament (ACL) reconstruction remains unclear. We hypothesised that BMAC and PRP combination could lead to better clinical results and better graft maturation/interface healing than PRP alone or conventional ACL reconstruction without any other biologic augmentation.MethodsIn this randomised double-blind prospective study, patients undergoing ACL reconstruction surgery were randomly assigned into three groups: (1) control group (without any biologic augmentation), (2) PRP treatment group, and (3) combined BMAC and PRP (BMAC + PRP) group. Moreover, they were evaluated using the clinical functional score, laxity examination, and magnetic resonance imaging (MRI) analysis.ResultsNo significant difference was observed in the improvement of functional scores among groups. However, laxity improvement at 24 weeks showed a significant difference with the BMAC + PRP group having the lowest laxity. MRI analysis showed no significant change in whole graft maturation among groups. In particular, the BMAC + PRP group showed delayed signal peak and higher graft signal at 24 weeks compared with the other two groups; however, the difference was not significant. With regard to tendon–bone interfacial healing, the BMAC + PRP group showed significantly wider tendon–bone interface in the femoral bone tunnel at 24 weeks compared with the other two groups. Moreover, the BMAC + PRP group showed significantly higher peri-tunnel edema signal in the femoral bone tunnel at 12 weeks compared with the other two groups.ConclusionPRP alone and BMAC and PRP combination showed limited enhancing effect in clinical function, graft maturation and tendon–bone interfacial healing compared with control (no additional treatment). When BMAC is used in ACL reconstruction, the possibility of greater inflammation in the early stage to graft maturation and bone tunnel healing should be considered.

MULTICELLULAR SPHEROID ENGINEERING USING BIOINSPIRED MATERIALS FOR OSTEOCHONDRAL TISSUE REGENERATION

Recently, technologies to culture one or more cell types in three dimensions have attracted a great deal of attention in tissue engineering. Particularly, the improved viability, self-renewal capacity, and differentiation potential have been reported for stem cell spheroids. However, it is crucial to modulate spheroid functions with instructive signals to use multi-cellular spheroids in tissue engineering. We have been developing ECM-mimicking fibrous materials decorated with cell-instructive cues, which were incorporated within 3D stem cell spheroids to fine-tune their functions as modular building blocks for bottom-up tissue-engineering applications. In particular, we created composite spheroids of human adipose-derived stem cells (hADSCs) incorporating nanofibers coated with instructive signal of either transforming growth factor-β3 or bone morphogenetic growth factor-2 for chondrogenesis or osteogenesis of stem cells, respectively. The bilayer structure of osteochondral tissue was subsequently mimicked by cultivating each type of spheroid inside 3D-printed construct. The in vitro chondrogenic or osteogenic differentiation of hADSCs within the biphasic construct under general media was locally regulated by each inductive component. More importantly, hADSCs from each spheroid proliferated and sprouted to form the integrated tissue with interface of bone and cartilage tissue. This approach may be applied to engineer complex tissue with hierarchically organized structure.

A NOVEL BIOMIMETIC BONE ADHESIVE: TRANSLATION FROM SMALL TO LARGE ANIMAL PRECLINICAL MODEL ON THE PATH TO FIRST IN-HUMAN USE

Surgeons treating fractures with many small osteochondral fragments have often expressed the clinical need for an adhesive to join such fragments, as an adjunct to standard implants. If an adhesive would maintain alignment of the articular surfaces and subsequently heal it could result in improved clinical outcomes. However, there are no bone adhesives available for clinical indications and few pre-clinical models to assess safety and efficacy of adhesive biomaterial candidates. A bone adhesive candidate based on water, α-TCP and an amino acid phosphoserine was evaluated in-vivo in a novel murine bone core model (preliminary results presented EORS 2019) in which excised bone cores were glued back in place and harvested @ 0, 3, 7, 14, 28 and 42days. Adhesive pull-out strength was demonstrated 0–28 days, with a dip at 14 days increasing to 11.3N maximum. Histology 0–42 days showed the adhesive progressively remodelling to bone in both cancellous and cortical compartments with no signs of either undesirable inflammation or peripheral ectopic bone formation. These favourable results suggested translation to a large animal model.A porcine dental extraction socket model was subsequently developed where dental implants were affixed only with the adhesive. Biomechanical data was collected @ 1, 14, 28 and 56 days, and histology at 1,14,28 and 56 days. Adhesive strength assessed by implant pull-out force increased out to 28 days and maintained out to 56 days (282N maximum) with failure only occurring at the adhesive bone interface. Histology confirmed the adhesive's biocompatibility and osteoconductive behavior. Additionally, remodelling was demonstrated at the adhesive-bone interface with resorption by osteoclast-like cells and followed by new bone apposition and substitution by bone. Whilst the in-vivo dental implant data is encouraging, a large animal preclinical model is needed (under development) to confirm the adhesive is capable of healing, for example, loaded osteochondral bone fragments.Acknowledgements: The murine study was supported, in part, by the Swedish Foundation for Strategic Research (#RMA15-0110).

The effect of posterior dental implant angulations in all-on-four treatment concept on the stresses induced at implant/crystal bone interface using glass fiber reinforced composite framework: Three‑dimensional finite element analysis

The effect of posterior dental implant angulations in all-on-four treatment concept on the stresses induced at implant/crystal bone interface using glass fiber reinforced composite framework: Three‑dimensional finite element analysis

The force at the implant cannot be assessed by the mallet force-Unless supported by a model.

The implantation of uncemented prostheses requires the application of sufficient forces to achieve a press-fit of the implant in the bone. Excessive forces have to be omitted to limit bone damage. Force measurements along the force transmission path between mallet and implant are frequently used to investigate this trade-off. Placing a load cell at a position of interest (PoI), which might be the implant bone interface or the head taper junction, is technically challenging or even impossible so that nearby positions are chosen. Thus, a certain inertia and stiffness remain between the PoI and the sensor, and consequently the measured dynamic forces differ from those at the PoI. This experimental and numerical study aimed to investigate the amount of force reduction along the transmission path while joining femoral heads to stem tapers. Forces were measured in vitro at the tip of the mallet, directly above the polymer tip of the impactor and below the stem taper. Springs and masses were used to represent the responding tissue of a patient. A semi-empirical numerical model of the force transmission path was developed and validated in order to simulate a larger range of responding tissue properties than experimentally possible and to investigate the influence of different surgical instruments. A distinct attenuation was observed since the peak forces at the impactor reached 35% of the applied peak forces and 21% at the stem taper, respectively. The force curves were replicated with a median root mean square error of 3.8% of the corresponding mallet blow for the impactor and 3.6% for the stem. The force measurement position and the used surgical instruments have a strong influence on the measured forces. Consequently, the exact measurement conditions with regard to sensor positioning and used surgical instruments have to be specified and hence only studies with similar setups should be compared to avoid misestimation of the forces at the PoI. The proposed dynamic numerical model is a useful tool to calculate the impact of the chosen or changed mechanical parameters prior to executing experiments and also to extrapolate the effect of changing the applied forces to the resulting forces at the PoI.

Analysis of the Effect of Thread Depth in Four Different Thread Designs on the Stress Distribution at the Implant-bone Interface Using Finite Element Analysis – A Comparative Three-Dimensional In vitro Study

ABSTRACT Statement of Problem: Treatment with dental implants owes much of its success to the development and maintenance of an osseointegrated bone-implant interface. The development of this interface is influenced by various factors, of which implant thread design plays a dominant role. Purpose: The purpose of this study is to analyze the effect of thread depth in four different thread designs on the stress distribution at the implant-bone interface using three-dimensional finite element analysis. Materials and Methods: Four implant models with different thread shapes, namely V thread, square thread, buttress thread, and reverse buttress thread with an uniform thread depth of 0.4 mm were designed. These models were then placed in the mandibular first molar region. Force of 100 N was applied axially and at 45°angle to the implant. Von Mises stress was measured at the implant – Bone interface area and compared for the different designs. Results: The color plots obtained were studied and the maximum Von Mises stress was noted and tabulated for each condition. Stress distribution in the finite element models comes in the numerical values and in color coding. Maximum values of Von Mises stress are denoted by red color and minimum value by blue color. In between, the values are represented by bluish green, green, greenish yellow, and yellowish red in the ascending order of stress distribution. Conclusion: Thread design plays an important role in stress distribution in implant and bone. Varying Von Mises stress is seen at the cortical bone-implant and cancellous bone-implant interface. Clinical Implication: Successful osseointegration is necessary for implant success and thread design plays a very important role in osseointegration. Therefore, the selection of implants with proper thread design contributes greatly to the success of an implant-retained prosthesis.

Stability, biomechanics and biocompatibility analysis following different preparation strategies of hierarchical zeolite coatings on titanium alloy surfaces.

Traditional titanium alloy implant surfaces are inherently smooth and often lack effective osteoinductive properties. To overcome these limitations, coating technologies are frequently employed to enhance the efficiency of bone integration at the implant-host bone interface. Hierarchical zeolites, characterized by their chemical stability, can be applied to 3D-printed porous titanium alloy (pTi) surfaces as coating. The resulting novel implants with a "microporous-mesoporous-macroporous" spatial gradient structure can influence the behavior of adjacent cells; thereby, promoting the integration of bone at the implant interface. Consequently, a thorough exploration of various preparation methods is warranted for hierarchical zeolite coatings with respect to biocompatibility, coating stability, and osteogenesis. In this study, we employed three methods: in situ crystal growth, secondary growth, and layer-by-layer assembly, to construct hierarchical zeolite coatings on pTi, resulting in the development of a gradient structure. The findings of this investigation unequivocally demonstrated that the LBL-coating method consistently produced coatings characterized by superior uniformity, heightened surface roughness, and increased hydrophilicity, as well as increased biomechanical properties. These advantages considerably amplified cell adhesion, spreading, osteogenic differentiation, and mineralization of MC3T3-E1 cells, presenting superior biological functionality when compared to alternative coating methods. The outcomes of this research provide a solid theoretical basis for the clinical translation of hierarchical zeolite coatings in surface modifications for orthopedic implants.

Enhancing the fretting damage resistance of suspension plasma sprayed hydroxyapatite coating with Titania addition

The damage of the bioactive HAp ceramic coatings on titanium implants and debris generated at the implant stem-bone interface is a major concern as it causes osteolysis, metallosis, and loosening of implants. Attempts are made to develop strong and wear-resistant biocompatible HAp coatings through the addition of different ceramics and with better coating processes. The addition of titania to HAp was found to strengthen the coating, and this paper reports the fretting wear resistance of titania-added HAp suspension plasma spray coating. Expected micro motion between the stem–bone interface in the implants due to applied loads is estimated using numerical simulations. The fretting wear resistance of the titania-added coating was evaluated using the simulated ball-on-flat contacts. The titania-added HAp suspension plasma spray-coated samples exhibited reduced fretting friction coefficient and increased wear resistance. High hardness and modulus of the 50 % titania added HAp contribute to the reduced fretting damage and wear debris generation at the interface.

Titanium Versus Carbon-Fiber Reinforced Intramedullary Nailing for Humeral Bone Tumors.

Multiple techniques have been described to treat humeral diaphyseal bone tumors requiring curettage or excision. Recent studies have suggested that carbon-fiber-reinforced polyetheretherketone (CFR-PEEK) intramedullary nails (IMNs) may be preferable to titanium IMNs for patients with musculoskeletal tumors due to CFR-PEEK's high tensile strength, radiolucency, a modulus of elasticity closer to native bone, and improved postoperative surveillance/radiation dosing. In this study, we describe the rate of fixation failure for both CFR-PEEK and titanium humeral IMNs when used for humeral diaphyseal bone tumors requiring curettage or excision. This was a single-institution retrospective cohort study including 81 patients (27 CFR-PEEK and 54 titanium) treated for a humeral diaphyseal bone tumor using an IMN +/- methylmethacrylate between January 2017 and December 2022. Primary outcome was revision surgery due to soft tissue complications, non-unions, structural complications such as periprosthetic fracture or IMN breakage, periprosthetic infection, tumor progression, and implant failure due to rejection or fatigue. No failures were observed in either patients treated with titanium nails or patients treated with CFR-PEEK not requiring curettage. Fixation failure due to implant failure was observed in two cases - at 214 days and 469 days after surgery - where CFR-PEEK IMN was used for stabilization after a wide segmental resection for oncologic control with a cement spacer reconstruction. In both cases, the resection was larger than 6 cm, the remaining distal humerus was less than 5 cm, and failures occurred at the interface of the residual bone and spacer. Both patients were revised using a titanium distal posterolateral humeral plate fixed with screws and cables without any subsequent complications. One additional CFR-PEEK IMN required revision surgery after 744 days due to progression of the tumor and subsequent non-union. One revision surgery was observed after 63 days for the titanium IMN due to non-union and tumor progression. Humeral diaphyseal bone tumors requiring large segmental resection with small residual bone and a large cement spacer may fail via tension due to bending forces at the distal portion. In this clinical scenario, the use of larger diameter CFR-PEEK IMNs may be indicated when these are available. In the interim, use of intercalary allografts instead of cement spacers, additional fixation with a titanium plate distally, or the use of a titanium nail when using a cement spacer may be considered.

Combined Trochlear, Patellar, Medial and Lateral Condyle Fresh Osteochondral Allograft Transplantation: A Case Report

Background: This is a case report of a 41-year-old man with torsional knee trauma in 2019 and chondral lesions. Previous microfracture had failed, and the patient presented with a dull pain and knee effusion. Imaging revealed multiple focal lesions including trochlea, patella, medial condyle, and lateral condyle. Fresh osteochondral allograft (OCA) transplantation is a versatile treatment for large defects as it is based on mature, living hyaline cartilage attached to a bone interface. A patient with multiple chondral lesions is rare, and this report presents a case with multiple symptomatic large focal lesions in the knee that underwent a fresh OCA in all 3 knee compartments. Indications: Osteochondral allograft is indicated for patients who present with activity-related pain and recurrent knee effusion. Contraindications are patient clinical conditions that may lead to complications, such as tobacco use, inflammatory arthritis, or septic arthritis. Technique Description: After the chondral defect is exposed, an appropriate allograft Mega-OATS sizer (15-30 mm) is chosen. Cartilage and the subchondral bone are drilled until the desired depth. The donor allograft is drilled in the desired diameter, and excess bone is removed according to the previous measurements of the recipient site. The graft is advanced with firm pressure into the created socket. Postoperative rehabilitation includes a limited range of motion and proprioceptive weightbearing in the first 2 weeks but expected total weightbearing and a full range of motion by the sixth week. Results: Range of motion was full by 6 weeks of surgery. The effusion lasted for 2 months after the surgery. Fresh OCA is a good surgical option for patients with multiple large chondral defects. Discussion/Conclusion: Patient satisfaction is high since the mature cartilage leads to a fast rehabilitation compared with the other surgical procedures for large chondral defects. This technique appears to be effective also for multiple focal lesions as presented in this article. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form.

Three‐dimensional printed Zn2SiO4/sodium alginate composite scaffold with multiple biological functions for tendon‐to‐bone repair

AbstractThe intricate nature of the tendon–bone interface poses significant challenges for current surgical methods aimed at repairing tendon–bone interface injuries. Despite notable progress in surgical techniques, these methods continue to grapple with hurdles such as complications and suboptimal healing effects. In this study, we prepared a three‐dimensional‐printed composite scaffold by incorporating bioactive ceramic zinc silicate (Zn2SiO4) into sodium alginate (SA) hydrogel. The physicochemical properties and mechanical strength of the SA hydrogel scaffold composited with Zn2SiO4 (ZnSi/SA) were investigated in vitro. Impressively, the 0.5‐ZnSi/SA scaffold exhibited a sustained release of Zn and Si ions, while exhibiting mechanical properties compatible with tendon–bone interface repair. Moreover, cell viability, cell migration, and osteogenic differentiation assay results showed that 0.5‐ZnSi/SA scaffold facilitated the viability, mobility, and osteogenic differentiation of bone marrow stromal cells. In parallel, assessments of cell viability, cell migration, and tendon differentiation indicated that 0.5‐ZnSi/SA scaffold promoted the viability, migration, and tenogenic differentiation of tendon stem/progenitor cells. Moreover, cell viability, cell migration, and tube formation assay results demonstrated that 0.5‐ZnSi/SA scaffold enhanced the viability, migration rate, and angiogenic performance of human umbilical vein endothelial cells. Collectively, our findings suggest a promising therapeutic avenue employing ZnSi/SA scaffold for tendon–bone interface healing.

Impact of the adjacent bone on pseudarthrosis in mandibular reconstruction with fibula free flaps

BackgroundMechanical and morphological factors have both been described to influence the rate of pseudarthrosis in mandibular reconstruction. By minimizing mechanical confounders, the present study aims to evaluate the impact of bone origin at the intersegmental gap on osseous union.MethodsPatients were screened retrospectively for undergoing multi-segment fibula free flap reconstruction of the mandible including the anterior part of the mandible and osteosynthesis using patient-specific 3D-printed titanium reconstruction plates. Percentage changes in bone volume and width at the bone interface between the fibula/fibula and fibula/mandible at the anterior intersegmental gaps within the same patient were determined using cone-beam computed tomography (CBCT). Additionally, representative samples of the intersegmental zones were assessed histologically and using micro-computed tomography (µCT).ResultsThe bone interface (p = 0.223) did not significantly impact the change in bone volume at the intersegmental gap. Radiotherapy (p < 0.001), time between CBCT scans (p = 0.006) and wound healing disorders (p = 0.005) were independent risk factors for osseous non-union. Preliminary analysis of the microstructure of the intersegmental bone did not indicate morphological differences between fibula–fibula and fibula–mandible intersegmental bones.ConclusionsThe bone interface at the intersegmental gap in mandibular reconstruction did not influence long-term bone healing significantly. Mechanical and clinical properties seem to be more relevant for surgical success.

Biomechanical behavior of carbon fiber-reinforced polyetheretherketone as a dental implant material in implant-supported overdenture under mandibular trauma: A finite element analysis study.

Implant-supported overdentures are well-known and widely accepted treatment modality to increase retention which is a crucial factor for determining patient satisfaction. The placement of two implants in the anterior region can be selected as a first-line treatment in patients with the atrophic mandibular ridge. The purpose of this research was to assess the biomechanical effects of carbon fiber-reinforced polyetheretherketone (CFR-PEEK) implant-supported overdenture in the event of 2,000 N forefront trauma to an atrophic edentulous mandible by using the finite element analysis method. Three types of mandible models were simulated; the first one was an edentulous atrophic mandible model; in the second model, 3.5 × 11.5 mm CFR-PEEK implants; and in the third model, 4.3 × 11.5 mm CFR-PEEK implants were positioned in the region of the lateral incisor of the identical edentulous atrophic mandible. Maximum Von Misses stresses 979.261 MPa, 1,454.69 MPa, and 1,940.71 MPa and maximum principal stresses 1,112.74 MPa, 1,249.88 MPa, and 1,251.33 MPa have been detected at the condylar neck area and minimum principal stresses - 1,203.38 MPa, -1,503.21 MPa, and - 1,990.34 MPa have been recorded at the symphysis and corpus regions from M1 to M3, respectively. In addition, the M2 and M3 models showed low-stress distributions around the implant-bone interface, particularly where the implants were in contact with cancellous bone. The results showed that the insertion of different diameters of CFR-PEEK implants led to low and homogenous stress distribution all around the implant-bone interface and stresses transferred directly to the condylar neck areas. Therefore, it was observed that CRF-PEEK implants did not change the basic behavior of the mandibula in response to frontal stresses.